Lead-in for radio receiving apparatus



Jem. 14,l 1930. J. A. Ros'rRoN LEAD-IN FOR RADIO RECEIVING APPARATUS Filed March '7, 1924 Eff/@i1 or a 7 a@ 7 7 ai. www f @d r @W Jas iig Patented Jan. 14, 1930 JOSEPH A. ROSTRON, OF CAMBRIDGE, MASSACHUSETTS LEAD-IN :FOR RADIC RECEIVING APPARATUS Application filed March 7,

'lhis invention provides an improved Lead-in.for radio receiving apparatus and 'process for making the same. This term, as popularly used and as employed herein, re-

lates to the device for making electrical connection between that portion of radio apparatus which is located outside of a building and the portion located within.

Heretofore where the necessity for having such a connection has arisen it has been the common practice to make a hole through the wall of the building, usually through a window or door casing, through which is led the wire that comes down from the antenna.

Such holes are disfiguring, and in many cases constitute unpermissible damage to property. For this reason in some cases owners of receiving apparatus have to be content with indoor aerials, where it is not permissible t0 leave a window open for passage of the conductor.

It is among the objects of the present invention to provide a lead-in that requires no opening in the building wall, speaking in al practical sense. Actually, and technically,

there is an opening, but the practical'eifect of having no opening is gained by passing the conductor through a closed natural opening such as a door or window opening. A s

the currents of electricity which iiow from and to the antenna in an ordinary domestic receiving apparatus are extremely small it is important that the 1ead-in have low resistance. The invention takes advantage of the fact that the alternating currents are largely in the surface of a conductor, and the further fact that there is usually a crack, however small, between a window and its casing. It has been discovered that by making the con'- ductor in the form of a thin metallic strip a device is provided which has a very large surface, relative to its area of cross section, and sufhcient mechanical strength, and yet which may have one of its dimensions so close to zero that it and its insulation can be installed in the space which ordinarily exists between the sash of a closed window and its 'casing without preventing the normal lockingof the window. Sucha strip mnstfit the contour of the window casingV with con- 1924. Serial No. 697,668.

siderable accuracy where it passes around the sash; and it is a matter of common experience that the angle and dimensions of these sur-` faces vary in different houses. It is a feature of the invention to provide so that the device is made automatically correct for the particular place where it is to be fitted, by a simple manipulation which can be carried out by the person who is to use the apparatus, without careful measurement and technical skill. The introduction of such a strip, into a place where there is supposedto be no space, as in the case of a tight fitting window, may entail considerable mechanical stress on the lead-in, and not infrequently some degree of disruption. It is a feature. of the invention that the lead-in accommodates itself t this, without the fragile strip which affords the electrical connection being destroyed. The retention of the conductor in place when the window is open, and the sash removed from its immediate support, is a matter of importance, particularly when the lead-in isset over the top sash as is preferred; 'and this also is cared for by the in- Vvevntion which provides so that upon the opening of the sash a cleavage naturally occurs between the device and the sash; and the device tends to hug the casing rather than the sash.

These characteristic results are preferably attained by enclosing the thin metallic ribbon between ribbons of insulating tape.. The tape may preferably be of adhesive nature, impregnated with a cement which canbe extruded; and overlyingeach tape strip 1s a strip-of externally non-adhesive and preferably slippery insulating fabric such as silk. At the ends of this laminated strip of-conducting and insulating material the conductor is iirmly secured to terminals for electrical connections. In the instance illustrated thterminals are clips of a well known type, riveted tothe composite strip, mechanically binding the copper, tape and' v silk' layers firmly together, and having sprlng clamps for engaging the wires.

The lead-in as a whole may be placed 0n a window sill, orpreferably over the top of, the upper sash of the Window. If then the metal which has been provided in the ribbon be soft, yet having a slight measure of resilience, a person may close `the window so as to deliver a smart blow upon the lead-in,

' to the window frame but not to the window sash. When the window is again opened, the lead-in ordinarily remains in place without special fastening, being held primarily by the cement and by its own resilience, or ultimately (if accidentally pulled away) by the outdoor and indoor wire 'connections'. The softness of the metal permits of its being molded and becoming set by these simple means; the slight resilience of the metal expands it laterally against the window frame as a socket, tending to spring slightly away from the sash, so Ythat the cleavage occurs between lead-in and Sash; and the dust, impalpable or otherwise, on the top of the win-l dow sash' prevents the cementitious adhesion of the silk to the sash.I The device can accordingly be located readily and easily where most convenient, and without damage to the building.

It is intended that the patent shall cover,

by suitable expression in the appended claims,

whatever features of patentable novelty exist in the/invention disclosed.

In the accompanying drawing:

Figure 1 is a plan of a lead-in embodying vthe principles ofthe present invention;

l Figure 2 is a section taken on line 2 2 of Figure 1, enlarged, and with the dimensions of thickness somewhat exaggerated for clearness; and V Figure 3 is a perspective showing how the lead-in may be used with an ordinary win- Referring to the drawings, a thin strip 10 of goodtconducti'ng material, such as copper, for example, soft enough to be easily ent and set, and yet slightly resilient, is7 enclosed between two strips `12 of tape im pregnat-ed with adhesive rubber or other insulating composition. Each of the latter strips being somewhat wider than the copper strip, their overlapping edge portions ad-v here together; and thus is formeda complete enclosure for the conductor. Strips 14 of fabric which is preferably externally nonadhesive, slippery, and of good insulating qualities such as silk, overlie the tape. These may be non-adhesive on their inner faces also, being held to the tape by its cementitious impregnation. These fabric layers prevent external exposure of the sticky tape during handling and during use if desired add to the insulation of the conductor; add finish to the external appearance; and serve to protect the physically weak conductor ribbon from rupture in the process of molding or stamping it` into new shape which in some instances acmetallic conductor ribbon 10 doubled over` upon itself, made wide enough to receive an eyelet 20and by this means riveted along a relatively long circular line to a spring"` clip 18 of well known typecomposed of a body piece of resilient metal doubled on itself to form a spring jaw, one 18a of whose members is slotted to co-act with a protruding loop tongue 18b bent out from its other member.

The lead 15 from the' antenna wire maybe clamped in this clip. Similarly the indoor wire 21 of the system is fastened to the other end of the lead-in.

With the wires either already or afterward thus attached, the lead-in is to be installed in a wall by setting it in one of the regular openings thereof having a seatable closure, as for y example by being laid over the top of a window 22, or across the sill; and the window is then to be closed in such manner as either lto deliver a sharp hammer like blow upon the lead-in, or at least'a powerful if slow seating pressure, as a stamping press upon its work. This stamps or molds the lead-in into shapes or sections having the precise angular and dimensional relations of thev surfaces along whichit is to lie, in order to accomplish the end of fitting into the crack so perfectly that the window can be closed with its usual tightness, s'o as to be locked, as usual. The leadin has thusbecome molded into the shape of casing 24, and simultaneously installed. Upon the window being again opened the lead-in usually remains next to the casing because of the shape it has acquired during the molding, which tends to hold it within the depressions of the casing. Its resilience makes it tend to expand against the recess walls; and the extruded cement tends to hold it there; but if it be pulled away by hand, the

vthe crack between the window. 22 and its Y wires 15, 21, attached'to its terminals and to adjacent insulators 26'will hold it nearby ready for thel next closing of the window. If

the Window were closed with a shake quick and powerful enough, the cementitious material within the inner insulating strips 12 would be forced into the `outer insulating layer 14 and extruded through it so as to cement the whole to the Window frame. In .this respect it has been discovered that the lead-in adheres to the frame and not to the sash, although obviously it was compressed against the sash with equal or greater pressure. I attribute this to the fact that in every Window there is a crack over the sash, through which more or less air is always' passing, from `Which air there is depositeddust which by gravity rests as a layer on the sash and does not rest on the frame immediately above it. If necessary or desired a thin layer of dust or powder may be separately applied for this purpose.

If the window fits its frame unusually closely, there may be severe stress imposed on the lead-inv when the Window is closed. In such case the silk exterior minimizes the internal stress by slipping readily over the adjacent sash and frame surfaces. It is preferred to make the silk of rather thin stock, in which case, if the stress becomes sufficient, the silk becomes abraded so that slippage occurs upon the rubber or gum in the insulating tape as a lubricant.

In a typical example of a lead-in embodying the invention in its best form, a copper strip having a thickness of .O06 inch may be used in a Width of inch; the tape next to it may be a high quality of so-called friction tape, abundant-ly impregnated With rubber and a solvent in the nature of rubber cement, with the gum preserved from the hardening that occurs upon contact with air; and the silk covering may be'satin; the whole being pressed smoothly so that the surface rubber, pressed into the satin, solidies in a thin exterior layer in the silk, and has a liquid reserve, thus protected, which is ready to be extruded through the satin. I have found that such a structure, having a total thickness of .O20 to .O25 inch has the remarkable capacity for use in connection with close windows, above set forth.

Although described as a lead-in for a receiving set of radio apparatus, which is .expected to be its most general field of utility, it is obvious that its use is not limited to this.

The sheet copper ribbon is preferred to a parallel series of wires, or a ribbon of Woven wires, which might be used, because it utilizes to the full the limited space which is available for it to occupy when in use, producing maximum conductivity, and mechanical strength of metal with a minimum of space and cost for material and labor.

I claim l. A'thin and freely flexible, tough surfaced, insulated radio lead-in, comprising an extremely thin and iiexible ribbon of metal, and .extremely thin, tough and flexible ribbons of non-adhesive fabric encasing said metal, separated from it and attached toit by thin adhesive ribbons which intervene between the non-adhesive ribbons and the metal, covering the metal and themselves covered by said non-adhesive ribbons; said lead-in being adapted to lie across the Window casing at the top of a Window, in the normal crack around the Window sash when closed, and it having a ytotal thickness only equal to the Width of said metal, separated from it and attached to it by extremely thin adhesive ribbons Which intervene between the non-adhesive ribbons and the metal, covering the metal and themselves covered by the non-adhesive ribbons; said lead-in being adapted to lie across the Window casing at the top of a Window, in the normal crack around the Window sash when closed, and it having total thickness only equal to the Width of'said crack; and said slippery, non-adhesive encasing ribbons being adapted, by pressure applied by said Window sash, to become impregnated With adhesive from said adhesive ribbons Within the lead-in.

Signed at Boston, Massachusetts, this nineteenth day of February, 1924.

JOSEPH A. ROSTRON. 

